Sept. 25 (Bloomberg) -- When Mercedes-Benz named the very special version of its CLK coupe the Black Series, it was surely with a knowing wink. If you're reminded of the American Express Black Card, well, the similarities probably aren't coincidental. Both are aimed at consumers willing to pay just about any price for exclusivity.

The car is built on the more Visa-like CLK550, which has a base price of $55,675 and an engine output of 382 horses. Pretty prosaic when compared to the special edition's 507 horsepower and $135,000 price tag. And exclusive? Well, only 350 Black Series will reach the U.S. market. Mr. Jones down the block probably won't have one in his garage.

This twist in temperament arrives courtesy of AMG, Benz's performance arm. Every Mercedes model has an AMG version; the regular AMG offering of the CLK, for instance, is the CLK63, which costs almost $90,000 and produces 475 horsepower. AMG takes the regular models and coaxes extra horsepower from the engines, tightens suspensions and improves brakes' stopping power. Sportier cosmetic touches are added, too.

The result is faster, nimbler cars that are still refined.

The Black Series breaks the mold. Patterned on the Formula 1 Safety car, it obviously takes to the racetrack with equal -- or more -- aplomb than cruising the highway.

It's as if the CLK had been fed a diet of lean meat and steroids. There's even a bit of 'roid rage.

Let's say, just hypothetically, that a certain car writer found an open parking lot with nobody around, and turned off the CLK63 Black's traction control. Then gave the car a footfull of gas, sending all 465 pound-feet of torque to the rear 19-inch Pirelli P Zero Corsa tires, and abruptly twisted the wheel.

Faster, Nimbler

The result (still hypothetically of course) would be of a car's impression of Tonya Harding on ice -- while chasing after Nancy Kerrigan. Crazy figure-8s, and lots of sideways action.

You won't get that reaction in a regular Benz.

Put a CLK550 next to the Black Series, and the visual difference is akin to Robert De Niro's physique in Meet the Fockers versus Cape Fear. The plump lines of the regular coupe have been carved away, leaving hard straight lines. The wheel wells are beefed up like bulging biceps, and the rear end has grown a carbon fiber spoiler and four very serious-looking exhaust pipes.

The front gets a similar reworking. And the gorgeous, shiny wheels look as if they were made in Vulcan's forge.

No Back Seats

The interior gets the rough-and-ready treatment as well. Back seats? Extra weight, so forget about it. You'll find a carpet-covered hollow instead. The front seats are specially bolstered to put the squeeze on their occupants -- they'll keep you pinned to the seat at extra-legal speeds, though you probably wouldn't want to sit in them for a drive across the country.

There's no fussy wood in the interior either -- instead we're treated to attitudinal carbon fiber on the center console. The steering wheel itself announces that it takes performance driving seriously. The bottom is squared off so it doesn't get in the way of knees, and deep thumb grooves pretty much demand the correct hand position on the wheel. I love it.

As we pull away from that hypothetical parking lot, my passenger asks in a concerned voice, ``You put the traction control back on, right?''

Tight Steering

Yes. Why? Because the CLK63 really is best suited to the track; driving on regular roads demands strict attention. The steering is incredibly tight, and the suspension actually talks back to you -- something else I've never experienced in a Mercedes.

The transmission is a seven-speed automatic which can be controlled with steering-wheel paddles. It strikes me as a bit misgeared: First kicks over to second after a prolonged shudder, and I never really find the perfect gear when diving out of corners.

Nonetheless, the suspension is up to most any job, making every sharp curve feel almost too easy, goading you into taking it faster next time.

So is the Black Series necessary? No more so than a Black AmEx. You're not likely, on a daily basis, to need such a stratospheric spending limit. Nor are you likely to need to push the CLK63 to its limits of speed, braking and cornering. But if you're a certain type of person, you like knowing that you can.